MRI Fairly Accurate As Surrogate for CSF Biomarkers

Last Updated: December 27, 2012.
Magnetic resonance imaging is a fairly accurate screening tool for distinguishing between Alzheimer's disease and frontotemporal lobar degeneration, according to a study published online Dec. 26 in Neurology.

Corey T. McMillan, Ph.D., from the University of Pennsylvania in Philadelphia, and colleagues studied data from lumbar punctures and volumetric MRIs from 185 patients with a clinically diagnosed neurodegenerative disease consistent with AD or FTLD. The accuracy of MRI-based prediction of cerebrospinal fluid (CSF) total tau (tt) and β-amyloid (Aβ1-42) ratio (tt/Aβ) was tested using data which included neuroanatomic visualization and categorization of a subset of 32 patients with genetic or autopsy-confirmed AD or FTLD.

The researchers found that MRI-predicted tt/Aβ correlated strongly with actual CSF tt/Aβ. Both predicted and actual CSF tt/Aβ have extensively overlapping neuroanatomic correlates in each of the groups: low tt/Aβ, consistent with FTLD, correlated with ventromedial prefrontal regions and high tt/Aβ, consistent with AD, correlated with posterior cortical regions. In patients with known pathology and in clinically diagnosed patients with known CSF tt/Aβ levels, MRI-predicted tt/Aβ was 75 percent accurate at identifying underlying diagnosis.

"Our results suggest that MRI provides a reasonably accurate screening tool discriminating between AD and FTLD," the authors write. "MRI-based screening yields an acceptable anatomic distribution of disease and predicted CSF values that are similar to actual CSF values from a procedure that is perceived as less invasive and more easily repeated."